There are several possible reasons:
• The file name or path does not exist.
• The file is being used by another program.
• The workbook you are trying to save has the same name as a currently open workbook.

I went to debug it using the built-in debugger in Visual Studio (VS) and received an error that the class module cannot be loaded. I know it is finding the module because if I move it to a different location in my project, it specifies that it cannot find the module.

This got me thinking about the whole subject of httpModules and their deployment on a localhost webserver and also use in VS debugging and I now have the following questions as a new and aspiring .NET programmer -

1. Does using the VS debugger make a difference? Does for example the module need to be registered separately ahead of time somehow on the localhost? Does it make a difference that the web.config file, the class module for the LanguageModule and the page itself (as well as the App_GlobalResources files) are all inside the same VS project?
2. Does the httpModule need to be registered separately on the local IIS for the application? I mean, I'm sure it needs to be so registered if I am running the application in a browser outside of Visual Studio, - but what about from within VS using the debugger? Doesn't the built-in compiler in the Debugger handle this (registration)?
3. If none of the above are issues in using the VS debugger, how can I go about debugging why the module won't load?

Thanks everyone for your assistance. I hope this isn't too much of a newbie question for the esteemed company!

Thanks Richard for your answer. I can post it there as well, I was just not sure because this is more of a general question relating to VS and the debugger there and not so much having to do with the method shown.

I have a WCF Service (Ex name: MyWCFService) which has all the database access and business logic mechanism, which is hosted in IIS using BasicHttpBinding. This WCF service is created by me. One of my collegue also created a WCF service called JasonProxyService which consumes MyWCFService, converts the result into Jason and gives it to UI, UI is using Ajax. The JasonProxyservice doesnt have configuration (like in web config it doesnt have elements , etc, which is unusual for me), and this JasonProxyservice has only two files .svc and svc.vb added to an asp.net application which has the UI also (the asp.net application has all the UI and ajax etc). There is no interface for contract, the ServiceContract attribute is defined right on top of the class and the methods in the class are defined with OperationContract attribute on top of them. When I tried to add interace and define it as service contract and put the WCF service configuration in the webconfig file, simply the Ajax isnt working. Then I left that option.
The reason for keeping JasonProxyService and UI in the same project is to avoid cross domain, becuase Ajax doesnt allow cross domain and our organization also not interested in cross domain because of security. The developer who wrote JasonProxyservice has left the project. Now it has come to my plate. This is what the problem is. I am really struggling with it for a while.
For solution, as first step I wrote logger to understand what is the problem, I am getting the below exception, and I am new to the json world. Please help me. Below is my exception, any help would be really helpfull.

I resolved it, actually it was another problem so it was throwing exception because of a field in the database is not matching to what I am sending.
So that exception was unable to be read by the jason application. So this error.

I'm developing as ASP.NET web application and I use Crystal report for visual studio 2010, I installed it on my machine.
the application work correctly on my machine, but not like this on the server.
after I upload it to the server I fond this error

Could not load file or assembly 'log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=692fbea5521e1304' or one of its dependencies. The system cannot find the file specified.

I searched for "log4net" more and I found more releases
I upload it ot my bin folder on the server, but the error changed to:

Could not load file or assembly 'log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=692fbea5521e1304' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

I didn't found any compatible assembly to my application,

I developed this web application into 32 bit OS, and I upload it to a server machine which use Window server 2008 R2 64 bit OS

is it has relation with the error?
and How can I correct that error?
at last where I can fount the compatible assembly log4net version 1.2.10.0?

I'm developing as ASP.NET web application and I use Crystal report for visual studio 2010, I installed it on my machine.
the application work correctly on my machine, but not like this on the server.
after I upload it to the server I fond this error

Could not load file or assembly 'log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=692fbea5521e1304' or one of its dependencies. The system cannot find the file specified.

I searched for "log4net" more and I found more releases
I upload it ot my bin folder on the server, but the error changed to:

Could not load file or assembly 'log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=692fbea5521e1304' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

I didn't found any compatible assembly to my application,

I developed this web application into 32 bit OS, and I upload it to a server machine which use Window server 2008 R2 64 bit OS

is it has relation with the error?
and How can I correct that error?
at last where I can fount the compatible assembly log4net version 1.2.10.0?

My Application work on the local host without this assembly, but fire an error on the server, this error say:

Could not load file or assembly 'log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=692fbea5521e1304' or one of its dependencies. The system cannot find the file specified.

I downloaded the assembly from the internet and upload it to the server, then another error say:

Could not load file or assembly 'log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=692fbea5521e1304' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

how can I solve this error and where I found the compatible assembly log4net version 1.2.10.0?

HI All,
Please Explain me , if we select dropdownlist automatically get second dropdownlistDetails andif we select second dropdown list automatically get third dropdownlist details. my dropdownlist control present in gridview(EditItemTemplate field) like this...